For that beachy New Year's Eve, I'd probably go really simple, like clam-diggers/long shorts or a black sundress with a sparkly necklace.
Taking your family that far for a holiday is logistically difficult. These are my ideas on pulling that off:
Check out the packing cubes post to see if those would be helpful, then focus on one cube at a time.
This will cross your mind fleetingly several times between now and then. Make notes and find a place to put them. Pull them out a few weeks ahead of your trip and consolidate them into one list, maybe with a cup of hot tea on a grey and chilly day that has you wishing for summer. (But if you only get nice, crisp weather with clear skies in November, don't put it off!)
Set out a box or suitcase or bag long before you intend to begin packing. When something strikes you that you must take, toss it in there. When you do laundry, think through the fresh items before you put them away and toss anything that's going on the trip into the suitcase. When you get presents to give to them--straight into the suitcase. When you sit down to pack, the head start will feel really good.
Give your kids simplified lists. You may want to have control over what they wear for certain events, but for others you can say "bring me five outfits and six pairs of underwear" or whatever. Let them live with their choices, as long as they aren't outlandish.
Ask other family members what they're wearing New Year's Eve and for other events. It doesn't have to be a big convo, just ask and see if their answers spark any ideas.
Do a packing photo post a couple days ahead of time. It will force you to organize things, and you'll get good ideas.
When you get there, don't worry. Borrow things from relatives if you must, but focus on the experiences and family time.
Have fun!
